Reply by Minorhero

The pulleys should slide on by hand but it should be a snug fit and you should not be able to wiggle them around. On more then one occasion I have needed to use a bearing puller to remove pulleys that have been on a shaft for a while.

If your pulleys can wiggle then that is a really bad sign. If you are really lucky it is just the pulley that is worn. More likely your arbor is also worn. New pulleys can confirm that. Many pulleys I buy from McMaster Carr come painted on the inner diameter and that creates a snug fit that I often have to sand off just to get them on shafts. In your case that might make the difference between a loose pulley and a tight one. I suppose you could also try adding your own paint to build that layer up some if it is still too loose.